orthomyxovirus

The Spanish Flu Pandemic

The 1918 influenza A (H1N1) virus caused what may have been the most lethal pandemic in the history of humankind.1 Marc Lallanilla from ABC News recounts its grim tale, writing:

It started on a small military base in central Kansas, when one soldier came down with a fever. Within a few hours, about 100 soldiers had reported to the Fort Riley infirmary with the same complaint.

By 1919, one year later, the so-called Spanish flu had spread around the world, killing an estimated 50 million people, with more than 500,000 dead in the U.S. (That included 195,000 just in the single month of October 1918.) The disease took more lives than the black plague, and more than all the wars of the 20th century combined.2

Unlike most strains of influenza, which disproportionately kill juvenile, elderly, or already weakened patients, the 1918 Spanish flu mostly killed young adults. In fact, more than half of the deaths occurred in young adults between 20 and 40 years old.3,4 In order to identify the characteristics that made the Spanish flu so deadly for otherwise healthy people, microbiologists “resurrected” the virus from a well-preserved corpse buried in the permafrost of Alaska.5

In their study, the 1918 virus provoked the subjects’ immune systems to go into overdrive, causing immune proteins to be expressed at abnormally high levels and immune cells to attack the body — what immunologists call a cytokine storm.6 Since young adults have a relatively stronger immune system, this finding helped explain the unusual pattern of fatality associated with the 1918 Spanish flu pandemic.

After ravaging the world for about a year and killing 3 to 5 percent of the world’s population, deaths associated with the Spanish flu dropped abruptly (and somewhat mysteriously).7,8 Before long, the Spanish flu became what some historians called the “forgotten pandemic” — that was, until bird flu emerged in the mid-2000s.9 Both strains bear a number of genetic similarities, and both developed in birds.10 Is humanity on the verge of a second Spanish flu?

References: (1) Alex Santoso, Neatorama; (2) Marc Lallanilla, ABC News; (3) Molly Billings, Virology at Stanford University; (4) L. Simonsen et al., Journal of Infectious Diseases; (5ScienceDaily; (6) Darwyn Kobasa, et al., Nature; (7) Michael Anissimov, wiseGEEK; (8) John M. Barry, 2004; (9) Alfred W. Crosby, 2003; (10) Brian Handwerk, National Geographic.

Photo: courtesy of the Otis Historical Archives, National Museum of Health & Medicine; edited by E. K. Graham.

CDC Announces Discovery of New Deadly Virus

The Centers for Disease Control and Prevention (CDC)announced Friday they have discovered a new virus that killed an otherwisehealthy man last year in the United States. The agency published the announcement in its Emerging Infectious Diseases journal.

 CDC officials reported the Kansas man had tick bites. After becoming ill, the man was given medication for tick-borne illnesses. When his condition didn’t improve, his blood samples were sent to the CDC. The agency determined the man was infected with an unknown virus. CDC officials eventually linked it to the Thogotovirus group and named it the Bourbon virus. The man quickly developed multiple organ failure and died 11 days after developing symptoms.

CDC officials said they’re working with Kansas health officials to determine if other people are infected with Bourbon virus. They are also researching to better understand the virus and how it is spread.

This is the first time such a virus has caused human illness in the United States. It’s only the eighth time a Thogotovirus has caused symptoms in a person worldwide.  Viruses in this group have been linked to ticks and mosquitoes in Europe, Asia, and Africa.

Thogotovirus is a member of the Orthomyxovirus family, the same family as influenza virus. Like influenza virus it has a genome of six single-strands of RNA.  Most viruses have a genome with a single strand of either DNA or RNA.  Unlike influenza virus which is passed from human to human, the thogotovirus is transmitted by ticks.